Automatic common-battery telephone-exchange.



E. D. FALES.

AUTOMATIC COMMON BATTERY TELEPHONE EXCHANGE. APPLlCATlON FILED SEPT26| i906.

1 1 86563 Panted .1mm 13, 1916.

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E. D. TALES. AUTOMATIC COMMON BATTERY TELEPHONE EXCHANGE.

APPLlcmoN mio SWR2@ 1905. 1,186,563. melma ,me 13,1916. 3 sHEUs-snfi 3.

EDWARD D. FALES, OF CHICAGO,

ILLINOIS, ASSIGN 0B,

BY `MESNE ASSIGNMENTS, T0

FIRST TRUST AND SAVINGS BANK, TRUSTEE. 0F CHICAGO, ILLINOIS.

AUTOMATIC COMMON-BATTERY TELEPHONE-EXCHANGE.

Application filed September 26, 1906. Serial No.

To ZZ 'whom it may concern:

Be it known that I. EDwAnn D. FALES, a citizen of the lvnited States of America, and resident ot Chicago. Cook county, Illinois, have invented a certain new and useful Imarovement in Automatic Common-Battery lTelephone-xchanges, of which the following is a speciication.

My invention relates to automatic oi' semiautomatic telephone exchange systems in general, but more particularly to automatic or semi-automatic exchanges in which the switches are operated on the step-by-step principleand especially to common battery telephone exchanges in which connectors are employed for establishing connection with called subscribersl lines'.

Generally stated the tion is to provide an improved and highly efficient automatic or semi-automatic telephone exchange system.

Special objects of vmy invention are to object of my invenprovide an improved construction and ar-A rangement wlierebyfcurren for talking purposes may be supplied through the connectors without the necessity of employing more than four coils or relay windings for feeding current from the common battery to the talking'circuit; to provide an improved construction and arrangement whereby talking current is supplied through the 'front and baclbridge relays of the connectors without the necessity of employing certain devices which have heretofore been considered necessuch, for example, as differential readditional coils or windings in the bridges, and whereby the two front-bridge relays and the two back-bridge relays .of each connector are not onlysufficient .for feeding talking current to the talking circuit, .but are also sufficient for connecting and releasing purposes-that is to say, sutilcient for controlling the connecting and releasing operations of the connectors; to prosary, lays and yide an improved construction and arrangement whereby,

if the front-bridge or line relays are `energized simultaneously while the back-bridge relays are denergized, all switches which'may have been operated are then automatically released Aor restored to normal condition; to provide an improved construction and arrangement whereby if the front or the back bridge relays are deenergized, atter the two relay bridges are Specification of Letters Patent.

" with the release-spri Patented June 13, 1916.

energized, the switches are then also released or restored to normal condition; and to provide certain details and features of improvement andnovel combinations tending to increase the general efficiency and improve the service of a telephone exchange system of this particular character.

-To the foregoing and other useful ends, my invent-ion consists in matters illustrated in the accompanying drawings and hereinafter described and4 claimed.

In the accompanying drawings, Figure 1 is a diagrammatic perspective view of my improved connector. Fig. 2 is a diagrammatic view in which the circuits and apparatus involved when two subscribers areiconnected are illustrated. The calling subscriberI is shown at A and the called subscriber at A. At the central ofiice the common battery B is shown, which supplies current for all switching purposes and for talking. The selector C allotted to the calling line is shown at the leftconnected with said line. A similar selector C of the called line is shown to the right, and, in addition, the connector D. Fig. 3 is a similar view of a modified form of the connector D.

The-substation A may be of any suitable or approved type. The one in connection with which I have elected to illustrate my invention comprises a receiver '2, a switchhook 3 for controlling-the substation circuits, which controlling operations are accomplished through the medium of any suitable means. such as the cam arms -L 5 and 6. The said substation comprises the usual transmitter T, induction-coil 8 primary winding 9 and secondary winding 10, the ringer 11. and condenser 1'2 in the ringer circuit. Being an automatic substation it is provided with the usual vertical and rotary impulse springs 13 and 1-1, and gs 15, 16 and 1T. Said provided with a substation is, of course,

but which is sedial, which is not shown 'cured to the shaft 18, together with the lock- Furthermore. there is a locking cam 2() that locks the dog 19 while the receiver is on the switch-hook to prevent a rotation of the dial. The substation ground circuit is normally broken between the ground springs 21 and '2Q by the cam arm-i, but when said springs are vtogether ground is pr/ovided to the ground post 23 and ing dog 19.

having the ries on the release spring 17, as is usually the case inl telephones of this type. For operating the limpulse .springs 1i and '14 the substatlonjs provided with animpulse Wheel 24 thatis secured to the shaft 18 which car-v its ,periphery the f'socalled vertical teeth and one rotary impulse tooth 26. The said impulse teeth are so arranged that when. the dial is drawn down the'impulse springs 1l and 13 are notl carried vinto contact with the'ground post 23, but as' the'dial returns, first the vertical "teeth engage 'the vertical impulse spring 13, and after they have completed their -work the rotary im-'v pulse tooth 26` operates the rotary impulse spring 1l. In this operation the subscribers vertical line conductor' 27- is first given a number of ground impulses, and then-the rotary line conductor 28 is given one ground impulse. It will be noticed that as long as 'granted March I3, 1906, to Keith', Erickson and Erickson.' yIn the drawingsboth selectors are similarlyv represented.

` posit ft-said bridgeauto' relay/pig and release magnet The line 'wipers and 32 andl the private wiper 33,' which are carried4 by the switchshaft, are shown; also the side switch wipers 34,35, 3S and 3T. 1n. normal position the said Wipers, of course,-engage the contact points 38, 40 and v'41; in second position the contacts 42, 43, 44 and '45, and in the third ations of the switch, while a call is being made, are, of course, 4controlled by the vertical and rotaryl'line relays 50 andl, which iii turn control' the vertical magnet private magnet rotary magnet 54 After the side switch passes to third position the release ot the selector, as iswell known, is con'- *fd through the medium of the lso-called bark -ielease relay 56. .As soon as the switch v i operated the switchshaft permits the offnornial springs 57 and 58 to come into contact, ubereby a guarding potential is estabi way of the private normal conductoi if) to the private bank contacts of the f cimnector. o prevent another subscriber freni interfering with the line, and from estil'ilisliing connection with the said line bv way of the normal line conductors 60 and When the otinorinal spring 57,

` however, is in normal position it rests in engagement with the spring ,62, whereby the bridgerut-ol relay G3 is retained in connect-ion with the private normal conductor 59, so that'whenever the' line. is' called the is energized,

the contactpoints 46, 47, 48 and 49.

v risees whereby theline relays 50 and 51I aredisconnected from the battery and from each other. y

The connector' D the, connector disclosed 815,176, granted March Erickson and Erickson.

chanical detai though'their functionsand the circuitsgare materially different. The usual switch-shaft 64. of .said connector yis vprovided with the i3, i906, ,to Keith,

' line wipers 65-and tand the private wiper' 'G'hwhich 'have allotted to their 'use' the linel The general me-v s are very much th same, al

is an improvement upon in Patent No.

and'private banks 68 and 69'. 'Said shaft is 'provided with 'the cam yteeth 71, circular teeth 7 2', normal post arm 73 and coil-spring 74, Saidvswitch'is also 'provided with vertical and rotary line relays 75 and l76 and the vertical and rotary magnets 77 and 78, the release magnet 79, private magnet 80, ringer relay 81, and the vertical 'and rotary back-'bridge relays 82 i and respectively.'v

The side 'switch E performs the yi'isual functions through the medium of the side switch wipers 84 85, 186l and 87.

For supplying ringing current .the einA change is provided with-a ringer generator F, while 'all other 'current' is'- provided through the battery B which 'h'asits positive terminal preferably grounded atG. In4 this system the ringing is done automatically and -.For that purposev the exchange is, furthermore, providedwith'an interruptor H for controlling'the energizing circuit of the.`

ringer relay 81. It will be understood, -of course, that the substations. Aland A', as disclosed in F ig. 2, are identical.'

The operation of the system is'as1fol-` lows: It will be assumed that the subscriber at substation VA Wishes to call the subscriber at A', the vnumber of which latter is 120. lVhen the recei'ver 2 is removed.'from the switch-hook 3 the cam armv, -upon leaving the spring l gages, permits the latter to leave the spring 89, thus breaking the ,ringing circ-uit, and the same operation permits" the primary cir- 'cuit s )rings 29 and 30 to come into contact. The rst digit being 1 the subscriber jopcrates yhis dial accordingly, and as soon as the dial is drawn down the groundsprings 21 and 22 come into contact, establishing a ground connection yfrom -the substation ground G1 to the ground pos't- 23.' As the dial returns, therefore, the impulse .wheel 24 thrusts the Vertical impulse spring 13 against the ground post 23 once, and'then the rotary impulse-tooth '26 in a similar manner carries ,the rotary impulse'spring 14 onto the ground post 23 once. The line conductors27 and 28 are, therefore, each grounded once, and as a y result the vertical line relay 50 ofthe selector C is first energized'by a flowl of current from thepsub- 7 0,- longitudinalv 88 over which it normally eli- 'the wipers onto some trunk line. ergizing circuit through the ground GrL to the ground poe4 station ground G1 through the ground springs '21 and 22 to the vertical impulse. spring 13, thence to the vertical line conductor "ZT, side citi-h wiper ill, contact point 38, verticai line relay 50, oridge-cutolf relay springs 9U and 91 to the battery lead 92 and through battery B to ground G. The vertical line relay then upon operatingl once presses the line relay springs 93 and 94 in contact, thus energizing the ver.- tical magnet 52 once by a lion' of current from round Gr2 through the Sinin'gs 94: and 93,. private springs and 9G to the vertical magnet thence to the battery lead 92 and from battery B to ground G. '1`heverticalmagnet 52, therefore, operates to raise the Shaft Wipers 31, 3'?. and 33 to the first level, in a Well-known manner. Thi?, operation having be'en accomplished, when the rotary line conductor grounded the rotary line relay 51 energized, and this in turn operates the'private magnet :33, which latter then trips the Side, switch to second position, establishing an energizing circuit through the rotary magnet .3l 'for rotating The enaaid rotary troni the substation t 3. thence to the rotary impulso spring il. rotary line conductor side switch Wiper 35%. contact point 239, rotary line relay 51,.bri:lgecut ofi' relay springa 9T, f90 and 91 to the batline relay 51 extend ltery lead 9i?. thence through battery B to ground G. "the aid rotary line relay upon zpressing tijd: spring 98 onto the spring Qt closes an energizing circuit through the priaa already stated, from the springs 9J: and 9S to the Said privatemagnet 5?), thence to the battery lead 92 and through battery B to ground The private magnet upon operating permite the side switch to pass to Second position, at which time the Side switch Wiper 41 engages the grounded contact point. #15, whereby the energizing cirsate magnet ground G2 through cuit Ator the rotary .magnet 5t is closed from ground l to the contact point 45, side switch Kiper interrupter springs 99, rotary magnet 51 to the battery lead 92, thence lullttf'Btof' il@ Tl tiiicugi )a erjY o biounc 1. ie ro magnetis then energized and the wip- GiS ill.

32 and 2? are carried into engagement. with the 'tiret trunk. lf the said trunk no?. busy, as Vis ivell ll'noivn,

the armature of the rotary magnet 5l ,by mechanically operating the armature ot the private magnet releases the .aide qwitch to third posithai. but if the Said 'lt' busy the private magnet energize.-` u the ALaarne time that the private armature isdepressed, and at the instant that the private Wiper 33 engages the grounded contact, sov that the side aivitch is held in second position and an eni i "cui-1L i@ maintained through the rotary magnet 3l: until the private wiper is carried onto the terminal ot an idle trunk and the energizing circuit. tor the private magnet destroyed. At the saune instant, of course. the side switch paf-aes to third po- S'ition and the wiper 3T leavee` the contact point l5. thus breaking the energizing circuit for the rotary magnet 5l and bringing the Selector to a standstill. The passage of the side switch to third position, ol course. carries the side Switch Wipers 31 and 35 onto the contact points 1G and li, and the line conductors 2T and :2S are placed in connection ivith the line wipers 31 and 32 which. having already entered int connection with the trunk conductors 10() and 101 that lead to the connector D. place the said conductors '2T and S also in connection with the Said connector l). The passage ot theA side Awitch to third position. furthermore, establishes a guarding potential 'at-the pri vate Wiper 33 when the side switch wiper ou engagea the grounded contact point This potential arrivee` at the said private iviper 3? trom the ground G* to the contact point l. through the Side switch wiper 3l), laxclterelease relay :lo to the private wiper 3?), thereby protecting.;y the trunk conductors lo() and 101 against seizure tor the, time being.

The said guarding potential, furthermore, sends a current through the ringer relay S1 of the connector l) from ground G* as traced to the private wiper 3l. thence over the said trunk conductoi1l)2. backbridge relay springe lll?) and lOl to the ringer relay o1. through the interrupteryH to the battery lead 9;). and through battery li to ground (i. The said ringer relay S1. ot' course. begins to operate intermittently each time that the interrupter H permits the closure ot said circuit. but the operation of the ringer relay Sl just at this time is of no consequence. The line conductoral 2T and having thus been extended to the connector D, the succeeding impulses from the substation A are directed to said connector D. The .second digit heilig 2 the subscriber operates his dial accordingly. grounding the vertical line conductor 1T twice and the rotary line conductor once. as already eX- plained. Each time that the vertical line conductor is grounded the vertical line relay of the connector D is energized by a flow of current trom the substation ground G1 to the vertical line conductor 2T, thence through the Selector side switch Iwiper 34 to the contact point 1G, vertical line Wiper 31` vertical trunk conductor 100 to the vertical line relay T5, thence through said re lay and lthrough the vertical back-bridge relay springs 105 and 106 to the battery lead 92, and from battery B to ground Gr. The vertical line relay -Tgeach time that it attracts its armature, "forces the line relay springsl' and 108 into' Contact, Aeach time- (see Fig;i 1), private springs 110 and- 111,A conductor 112, side switch wiper 84, contact'.

point A113 to the vertical magnet 77, thence' to .battery lead 92, and-through -battery to ground G. The vertical magnet, as disfenergizes the rotary line relay 76 of the conclosed in the aforesaid patent, when energized operates t'o raise the switch-shaft and' Wipers.. The vertical'mag'net being ener-A gi'zed 'twice the wipers 65, 'and' 67" are raised to the second. level. The ground impulse to the rotary line conductor-28, after the switch-shaft 64 has thus been raised,

nector, which in turnv operates to 'energize the-private inagnet80. The circuit' over which the 'said rotary linev relay 76, is energized extends from the substation ground G1. to .the rotary linevconductorl28, thence to the side switch wiper of thel selector C, contact point 47,v rotary .line-wiper 32, rotary trunk'conductor 101 to the' said rotary line relay 76, thence to battery lead 92 Vand through batteryB to ground Gr.

The rotary line relay 76 upon' attracting its' armature forces the spring 113 onto the spring'108, lwhereby a How 'of current 4is. `sent' through the private "magnet 80 from ground G, through the springs 108 and 113, conductor 114- to thel jprivate.magnetl 80,

thence*- through conductor 115, verticalv u through batteryB to' ground G. The said back-bridge relay spring's 105 and-"106 'to 'the batterylead 92,-thence through battery B' to. ground' G. The private magnet 80y l y line .relays 127 and 128-from thebatterylead '92, andlfrom each other. As soon as thelside upon' attracting its armature and then de-l ener'gizing operates, of course, to release the side switch E' from first to secondl position. The effect ofthe shifting of' the side switch is to substitute the rotary-magnet 78gfor the vertical magnet 7 7, bringing' the former under .the control of the vertical vlinerelay 'T5-when the side switch `wiper, 84' leaves the contact point'113 and engages the con.

'tact point 116. The-third digit beingO, when' the vertical lin'e conductor 27" is gro'unded'ten timesby the subscriber 'upon-4 operatingthe dial corresponding to the said' digit `0, the vertical line relay-` is energized ten times over circuits-that are described, whch relay Ain turn causes the stepriedl into engagement with the tenth terminal 'ot the second level, from which terminal lead the normal 'conductors '117,118

.thus been operated Athe ground 4impulse to, the rotary line conductor 28 energiz'esthe rotary line' relayl 76 of the 'connector-overv Vcircuits that are already Well known, .which relay 1n turn operates ,the private magnet .80, as before. A The said privatev "magnet upon energizing will, ,if the/line is busy, close a circuit through theeleaseV magnet 7 9to release the switch; but it will be assumed for the 'presentthat [the .line'isnotbusy and' that' the side syvitch E 'passes'to third position when the private magnet i80` denergizes,

. As 'soon as the side switch passes to third position a guarding potential is established at the private Wiperv67, when the side switch wiper engages the grounded contact point 120. This guarding potential prevents any1 other subscriber from calling-in on the line #120 for the time being. This guarding'po tential, furthermore, sends a) flow of cli-rrent` through the bridge-cut-otf relay 121l of the .selector C. This circuit extends as traced to the priv-ate Wiper 67- to the private normal '119, thence through theyswith-shaft springs 122' and 123Y tothe' bridge-cutfoll relay 121, thence to the'battery lead 92 and relay 1-21 upon -energizing'separates the' -sprin'gs 1.24, 125 and 126disconnectng the switch" wipers 86' and 87-pass into engagetended' to the. line wipers65 andV 6.6 and, therefore, each timelthatlv thering'er relay 81 energizes ringing current is vsentout to the' calle'd subscribers station from the lringer generator F through the ringer relay springs -133 and'134 to the side switch .wiperls'86 and .87, line wipers 65 and'66, normal conducto-rs' 117 and 118 to the :line conductors 135 and' 136 and throl'ighthe ringer 137. flVhen the subscriber at substation #120 answers, the primary lcircuit springs 138 and "139 then close in contact, establishing a circuit through' the transmitter 140, primary winding 141, in series'xvith the'back-bridge relays 8.2 and 83 of the-connector, and the said relays 8 2 and 83 therefore energize simultaneously. resistancecoil 142 at the connector D i" br ilged-.acros's the conductors 1.43 and 144. vbut the resistance of said coil is so high that the relaysSl Aand -83 do'not receive enough curi-,ent to operative-ly energize, them at the instant thatthe side switch passes to third It will be vnoticed that the nmv Yma

v101 engages the spring 115.

position. Then the subscriber answei's, however. and since the resistance through the transmitter 110 is much lower, the currcnt that passes through the said circuit is sullrient to operate the relays 8;' and 823. The springs 10T. 100 and 111l controlled by the back-bridge relay 82 are so adi usted that the spring 10.3 leaves the spring 100 and engages the spring 111 bctore the spring The object otl this arrangement is to energize the line relays T5 and T0 before the springs 101 and 115 come into contact. -\s soon asthe spring 105 engages the spring 111 an energizing circuit is established through the line relaysl T5 andi-0 in series. and current tlows from ground (l0 to the back-bridge relay springs 111' and 105, thence through the vertical line relay T5, vertical trunk conductor 100` through the transmitter Tand primary winding ff ot' the substation back to the rotary trunk conductor 101. thence through the iotary liiic relay T0 to the battery lead J2 and through battery B to ground (fr. As soon as the relays T5 and T0 energize the springs 110 and 11T separate. while the springs 11T and 118 engage in contact. The separation ot' the springs 116 and 11T occurs before the back-bridge relay springs 101 and 115 come into contact. and the called subscriber, therefore. controls the supply of talking Current to the calling substation. As soon as ythe front and ba'ck bridge relays T5, T0. S2 and 83 energize, the springs 103 and 101 separate, and also the springs 116 and 11T g'there- 'ore he energizing circuit for the ringer relay 'i is destroyed and the ringer relay springs 12j-S1 and 119, and also the springs 132 and 150, remain in contact. The subscribers being thus provided with talking current are able to converse with each other over the circuit that is indicated by the heavy conductors in Fig. 2. which circuit passes through the condensers 1.31 and 152 that divide the talking circuit into two sections, which sections provide the connected subscribers with talking current. It will be seen that the private magnet is short-circiiited while the subscribers are talking, and

the object in thus short-circuiting the private magnet is to prevent it from energizing. After the subscribers are through talking the calling subscriber may release the switches by restoring the i'eceiver 2 and thus causing the switch-hook 3, through the ineJ diinn of the arm 6, to press the releasesprings 15, 1G anrh17 into contact. The vertical and rotary line conductors 27 and 28 are thus grounded simultaneously from the substation ground (l to the ground release spring 17. from whence the current divides to the springs 10 and 15. passing to the rotary and vertical line conductors 2S and QT.

Since the inside terminal ot the vertical side of the line is grounded at G6, as already explained, the grounding of the said line at the substation short-circuits the vertical line relay T5 and, ot' course, the said relay denergizes. lf pon deinergizing the springs 110 and 11T come into contact while the back-bridge relay springs 101 and 115 remain in contact. Therefore a circuitis established through the release magnet T9 ot the connector. in series with the back-release relay 50 of the selector C. from ground at the selector side-switch to the Contact point 18. through the wiper back-releasff relay 50 to the private wiper 33, trunk release conductor 102.v vertical line relay springs 110 and 11T. through the backbridge relay springs 101 and 115 to the release magnet TIS), thence to the battery lead 92 and through battery B to ground G. The release magnet 79 upon attracting its armature releases the switch-shaft 01 and the side-switch E in the well-known manner. thus breaking the energizingcircuit through the back-bridge relays 82 and83, when the side switch wiper 85 leaves the grounded contact point 120. s soon as the said back-bridge relays denergize the springs 101 and 115 separate and the release magnet T0 denergizes, restoring the switch to normal condition and restoring the springs 101 and 103. and 106 and105 into normal contact. In the mean time the backrelease relay 56 ot' the selector, by pressing, the back-release relay springs 153'and151 into contact. energizes the release magnet 55, which latter attracts its armature and remains in readiness to release its switch as soon as the release magnet denergizes. The denergization of said release magnet occurs when the back-release, relay 56 Vdeenergizes at the moment that theA backbridge relay springs 101 and 115 of the connector D separate. It the called subscriber instead of the calling subscriber hangs up his receiver first, since the resistance-coil 112 lis bridged across the conductors 143 and 111 (Fig. 1) as previously. explained, the back-bridge relays 82 and 83 do notdenergize. because the current that passes through the resistance-coil 142 is sufficient to retain the relays 82 and 83 fn an operative condition. Therefore, the said resistance-coil 11'2is provided to prevent the called subscriber from taking any part' in the release. If the calling subscriber wishes to release when the connector side switch is in first or second position, or in third position,-bef'ore the called sutiscriber has answered and, therefore, befo e the relays 82 and 83 are energized-he does so by grounding the vertical and rotary line conductors '2Tand Q8 and thereby energizing the vertical and rotary line relays 75 and 76 shtml-- taneoiisly over circuits that have already been pointed out. Therefore, the springs 117 and 148 are brought into contact while the back-bridge l. currentis suppliedto the called sub- -m1ber`s line from battery B and through raid hack-bridge relays '82 Aand 83 direct, Y lldrin a' similar manner current is supplied -b calling subscriber through the line ll rdays and 76direct'fro1n battery B. l? substituting the connectorD (Fig. '3)' or the connector D .(Fig. 2) .the system is then similar to theone described in the Since al1 parts contained in the H connector D' are identical with .those containedjn the, connector Dthey are given like rmuierals. By the use 'of this modified connector the 'ca'lledsubscriber mayl also rethe connection to hisvline by simply up his receiver.y In -this case, as Soon as theV receiver breaks the circuit by Yseparating the springs 138v and 139 the re laysV 8 2 and- 83 ydenergize, pressing the 103 and'104- into contact before the SQ. rings 105 andl144 separate, or at about same tin1e,`in which case'a release circuit' is established through the release mag. net 79 and the back-release relay 56 of the leetor 'C before the line relay springs 147V and 148 separate. This circuit extends, as before, from ground G4. at the selector side switch through the back-release relay 56,' -trlmk releasecondu'ctor 102, through the back-bridge relay springs 103 and 104, line relay springs 147 and 148 to the release'l magnet 79, thence to the battery lead 92 and through battery B to ground G. As soon as i' the release magnet 79 energizes the connector 1s, of course, released as before, and as Soon as the line relay spr-ings 147 and 148 separate, because of the separation of the back-bridge relay springs 105 and '144, the releasecircuitis destroyed,rwhich causes a denergizationv of the back-release relay 56, `which in turn' produces a release lof the se- .lector C, as already pointed. out. It is evident, therefore, that after the subscribers are through talking, the denergization of Qthe front-bridge relays 75 and 76, or the der'lergizationv of the back-bridge relays 82 and 83, by the calling or called subscribers, will produce a vrestoration of the sw1tches.

In other words, if at any time the backbridge relay springs 103 and 104 come .into contact while the front-bridge relay springs 147 and. 148 -are in contact, a release will follow or if the front-bridge relay springs 146 and 147 come into contact while theback-bridge relay springs 104 and 145 are n mntact. a release -will fnllnw alsa ha ppensI to be busyA -cuit is broken as soon `as the 'As' is well known, busylines are protected by guarding potentials, and-- if thecalled line when the private magnet 80 'is energized .for the last time, as al# ready expained, the connector-switch D will be released at the instant that the private magnet springs-155 and 156 are brought'into contact, since the private wiper 67 is then 1n engagement with the. grounded contact. The release circuit extends from the grounded contactto the ,private wiper 67, thence to .the side switch wiper contact point `157, private magnet springs 155 and 156, release magnet 79 to the battery lead 92. thence through battery'B to ground G. The re,- lease magnet 79 upon energizing releases the connector-switch shaft and side switch, as -is well known, and, of course, thel release cirprivate wiper 67 leaves the-grounded contact point. The subscriber at the calling substation then receives a .busy signaling current from the busy machine Ito the conductor 158,-cone '.nector side switch contact point v159, side switch wiper85, rotaryback-bridge relay 83, condenser 152, rotary trunk conductor 101, through the primary .winding 9 at the substation A and back to the vertical line coni ductor 27,'thenc'e through the vertical line relay. 7 5 at the connector D tothe batter lead 92 and back to thebusy machine-fi- The subscriber will then hang, up his re-l "ceiver, grounding "both line conductors 27 and 28 and energizing the line relays 75'and 76 of the connector 'sim'ultaneou'sly, thus bringing the springs 147 and 1,48 into' con- 'tact while the back-bridge relay springs 103 and 104 are in contact, producing a release of the switches, as already explained.y ,It will. be understood that where a system is to he installed in'which ten thousand subscrib ers must be accommodated another selectorswitch must be insertedv between the selector C and connector D,.'a'nd the trunk conductor similar to the trunk conductor 102 leading from the private wiper 33 Vwould then lead t0 a backrelease relay spring similar to the back-release relay spring 153, and lthe said spring 153 would not then be connected to ground, as shown in Fig. 2. The back-release relay of the interposed .selector would, of course, likethe back-release relay 56, be connected with the connector D, as shown in Fig. 2; and then each'time that the backrelease relay of the said' interposed selector energizes, the release Inavnet simi-lar to the release magnet 55, 4upon the energization4 of the relay, would be `connected through springs similar to the springs 154 and 153 with the back-release. relay 56 of the selector 125 C, and the release would, of course, follow accordingly.

From the foregoing Ait will be seen that the two front-bridge relays and the two back-bridge relays of the. connector D are l" not only sufiicient for feeding curi-eilt to the lines for talking purposes. but are also sullicient for controlling the connecting and releasing operations of the connector. as well as the releasing of the other switch or switches back toward the calling telephone line. In this way I avoid the use ot' certain more or less expensive or undesirable devices which have heretofore heen considered necessary, such. for example. as the diti'erential relay windings or other additional coils in the front and bach bridges` of the connectors.

From the preceding it will be evident that the ringer relay S1. which energizes as soon as the side switch of' the selector C passes to third position. does so over a circuit which branches at the connector into two sections. one section. as previously described. extending through the back-bridge relay springs 103 and. 104 to the ringer relay and thence to the interrupte'r H to the battery. and the other circuit through the front-bridge relay springs 146 and 1-1'( to the said ringer relay.

. In order to destroy the ringer relay circuit.

therefore. it is necessary that the vertical front and back bridge relays T5 and 82 be energized at the same time.

` It has been explained that when the called subscribei answers, the front-bridge relays 7 5 and 7Gl energize owing to the engagement of the back-bridge relay springs 105 and 144". and that the sprmgs 146 and 117 of the front-bridge are separated before the springs 104 and 145 of the back-bridge engage. 'This may not be an exact statement rate the energizationl of the front-bridge relays T5 and 'T0 substation A engages occurs sufficiently' soon after the back-bridge relay springs 105 and 1-1-1 engage to prevent a release fr m occurring by the engagement of the bac -bridge relay springs 101` and 145..

It will be-noticed thatl the release, when the calling subscriber hangs up his receiver before the called subscriber. is dependent upon the deenergization of the vertical line relay 75. and more particularly upon the engagement ot' the front-brid ge relay springs 146 and 117. Therefore, whatever operation at the substation will cause the de'energization of the said relay 7.3 during a time that the back-bridge relay springs 101 and 145 vare kept in contact will produce a release.

is not absol therefore,

v necessary at this stage to produce a rel.i e. as the simple opening up of the subscribefs line conductors 27 and 28 will produce the same result, namely the denergization of the vertical line relay 75. which will, of course. as explained, produce the release. The opening up of the subscribers line circuit, it has been explained, occurs when the cam arm 5 at the the ringer. circuit the line conductors 27 and 28A .spring Se'. at which time the primary circuit springs 20 and 2X0 separate. leaving the subscribers line conductors normally open. This` in itseltl is sullicient to restore the switching apparatus at the central otlice. It therefore follows that either the grounding ot both sides oi the calling line or the opening up of the line will produce a release. l

In this system the rceistances ot' the various coilsy may be varied considerably, but I find that good results are obtained when the back-release relay 50 of the selector C is wound to a resistance oi' about one-halt ohm. while the release magnet T0 of the connector D is wound to a resistance of about sixty ohms. the ampere turns in both of these coils heilig sutlicient to perlnit them to energize in series with a battery B of about fifty volts. The ringer relay S1 may be of about threehundred and fifty to five hundred ohms. if desired. so that it may energize in series with the winding ofthe back-release relay 50 of the selectorl @but cutting down at the same time the amperage in the circuit so that the ampere turns ol the back-release relay 50 will not be sufficient to cause the energization of the said back-release relay 7a3. The front-bridge relays T5 and T0. or the vertical and rotary line relays as they are called. may bewound to a resistance of tive hundred ohms each,4 although a considerable variation maybe made. The back-bridge relays 822 and provided with a pair of iffe relays, a backof relays. a

bridge provided with a pair battery included in both bridges. step-bystep mechanism controlled by 'at least one of said relays. and release mechanism controlled by at least one of said relays. said relays constituting the sole or only artificial resistance between the battery and the said talking conductors.

Q. A telephone connector comprising a pair of voice-current conductors, an inductive connection in each conductor, a bridge in front of sai/l irfluctive connections, a bridge back oi said inductive connections, electrically-propelled and step-by-step-actuated connecting mechanism, y electrically l operated release mechai'iism. a battery included in both bridges. and four electromagnets included in said bridges, the windings ot' said electro-magnets constituting the sole or only artificial resistance between .'relays, and release mechanism the battery and the voice-current conductors.

3. In a telephone exchange system, the combination of a talking circuit, inductive connections in said circuit, a bridge in front of s aid inductive connections, a bridge back of said inductive connections, two relays in each' bridge, a battery included in both bridges, s witching mechanism controlled by at least one of said relays, release mechanism controlled by at least one of said relays, subscribers telephones receiving talking current from said' battery, and subscriberoperated means for controlling the energizing ofatleast one of said relays, thev .windings of saidrelays constituting the sole' or only artificial resistance between the battery and the saidtalking circuit. y

4. In a telephone exchange system, the combination of a talking circuit, an inductive connection in each side of the talking circuit, a bridge in front of said inductivelconnections, a' bridge back of said inductive connections, a pair of relays in each bridge, suitable means for supplying talking current through tie windings-of said relays to the talking circuit, subscribers telephones receiving the talking currentrlpplied through `the said relay windings, switching mechanismcontrolled by at least one of said relays, release mechanism controlled by at least one' of said relays, and subscriberoperated meansv for controlling the-ener gizing of vat vleast one of said relays, the said relay windings constituting the sole o r onlyI artificial resistance through which talking current ,is supplied tothev talking circuit.

5. A telephone connector provided with va pair of voiecurrent conductors, an 1n- "duetive connection l in. each conductor, a

bridge in front ofl said inductive connections, a bridge back of said inductive connections, apair of relays in each bridge, suitable means for supplyingv current through 'the windings of said relays to the said voice-current conductors, switching mechanism controlled by at least one 'of said controlled b v at least one of said relays, 'the windings of said relaysfconstituting the sole'or only artificialresistance through Awhich current is supplied to the said voice-current conductors.

(5. In a telephone exchange system, the combination ot',a calling telephone line, a' called'telephone line, a selector intermediate the two lines, a connector intermediate the selector and the called line, subscribers telephones'.y subscriber-operated means for controllling the selector and connector, and means for supplying talking current through the connector to the calling and called telephone lines, said connector provided with our'relay coils constituting the trolled by at least one of said bridged relays.

8. A telephone connector comprising a pair of voice-current conductors, an' inductive connectionin'each conductor, a bridge in front of said inductive connections, a bridge back of said inductive connections, electrically-prop'elled and step-by'-step actuated connecting mechanism, electrically operated 'release mechanism, a battery in- -cluded Iin both bridges', four electro-magnets included in said bridges, the windings of said electro-magnets constituting the sole orfonly 'artificial resistance between the battery and the vvoice-current conductors, and a` ringer relay controlled by at least one 'of said bridged relays.

9. In a telephone exchange system, the` combination of a talkingcircuit; inductive connections in said circuit, a bridO'e in front v100 of said inductive' connections, a bridge 'back of saidinductive connections, two relaysrin each bridge, a battery included in both`\ bridges, switching mechanism controlled by at least one of said relays, release' mechanism controlled by at least one of said re' lays, subscribers telephones receiving talking current from .said battery, subscriberoperated means for controlling the energizing of at least one of said relays, 'the windings of said relays constituting the sole or only artificial resistance between the battery and the said talking circuit, and a ringer relay controlled by at least one of said bridged relays.

l0. In a telephone exchangesystem, the combination of a` talking circuit, an inductive connection in each side of the talking circuit, a bridge in least one of said relays, the said relay windings constituting the sole or only artiicial resistance through which talking current is supplied to the talking circuit. and a ringer relay controlled. by at least one ot said bridged relays.

l1. A telephone connector provided with a pair of voice-current conductors, an in ductive connection in each conductor. a bridge in front of said inductive connections. a bridge back ot' said inductive connections. a pair of relays in each bridge. suitable means for supplying current through the windings of said relays to the said .'oice-current conductors, switching mechanism controlled by at least one of said relays. release mechanism controlled by at least one ot .said rela)v f, the u ii'ulings of said relays constituting the sole or only. artificial resistance through which current is supplied to the said voicecurrent conductors, and a ringer reisje controiied by at least one oil said bridged relays.

12. In a telephone exchange system, the combination of a calling telephone line` a 'alled telephone line. a selector' intermediate the two lines. a connector intermediate the selector and the called line` subscribers` telephones. subscriber-operated means for controlling the selector and connector. means for supplying talking current through the connector to the calling and called telephone lines. said connector provided with four relay coils constituting the sole or only artificial resistance through which talking current is supplied to the telephone lines. and a ringer relay controlled said bridged relays.

13. A telephone connector-switch provided with parallel voice-current conductors` a condenser in each conductor, a trontbridge provided with a pair of line relays, a

back-bridge provided with a pair of relays, a battery included in both bridges. step-bystep mechanism controlled by at least one of said relays, release mechanism controlled by at least one of said relays. said relays constituting the sole or only artificial resistance between thebattery and the said talking conductors, and means for connecting all of said relays with the same pole of the battery when the ,connector is released.

14. A telephone connector comprising a pair of voice-current conductors, an inductive connectionnin each conductor, a bridge in front of said inductive connections. a bridge back of said inductive connections, electrically-propelled and step-by-step-actuated connecting mechanism. electrically operated release mechanism, a battery included in both bridges, four electro-magi ets included in said bridges, the windings of said electro-magnets constituting the sole oronly artificial resistance between the battery and the voice-current conductors, and means for by at least one of connecting all o'l said relays with the same pole of the battery when the connector is released.

la. in a telephone exchange system, the ,ombination of a talking circuit, inductive connections in said circuit, a bridge in front ot' said inductive connections, a bridge back of said inductive connections. two relays in each bridge, abattery included in both bridges. connector switching mechanism controlled by atleast one of said relays, release mechanism controlled by at least one of said relays,-subscribers" telephones receiving talking current from said battery, subscriberoperated means for controlling the energizing of at least one of said relays, the windings of said relays constituting the sole or only artificial resistance between the battery and the said talking circuit, and means for connecting all of said relays with the same pole of the battery when the connector released.

16. In a telephone exchange system, the combination of a talking circuit, an inductive connection in each side of the talking circuit,' a bridge in front of said inductive connections, a bridge back of said inductive connections, a pair of relays in each bridge. suitable means for supplying talking current through the'windings of 95 said relays to` the talkingcircuit, subscribers telephones receiving the talking current supplied through th said relay windings. connector switching mechanism controlled by at least one of said relays, release mech-k anism controlled by at least one of said relays, subscriber-operated means for controlling the energizing of at least one of said relays. the said relay windings constituting the sole or only artificial resistance through which talking current is supplied to the talking circuit. and means for connecting all of said relays with the same pole of said means for supplying talking current when the connector is released.

17. A telephone connector provided with a pair of voice-current conductors, an inductive connection in each conductor, a bridge infront of said inductive connections, a bridge back of said inductive. connections, a pair of relays in each bridge, suitable means for .supplying current through the windings of said relays to the said voice-current conductors. switching mechanism controlled by at least one ovsaid relays, release mechanism controlled by at least one of said relays, the windings of said relays constituting the sole or only artificial resistance through which currentis supplied to the said voice-current conductors, and means for connecting all of said relays with the same pole of said means for supplying current when the connector is released.

18. In a-telephone exchange stem, the combination of a calling tele liyyne line, a |30 called telephone line, a selector intermediate the two lines, a connector intermediate the selector and the called line. subscribers telephones, subscriber-.operated means for controlling the selector and connector, means for-supplyingtalking current through the connector to the calling and called telephone lines, said connector provided with four relay.' coils constituting the sole or only artificial resistance through which talking current is supplied to the telephone lines, and means for connecting all of said relays with the same pole of said means for supplying talking current when the connector is released.

19. An automatic telephone connector provided with a release circuit having two parallel and normally open branches, parallel voice-current conductors, inductive connections in said voice-current conductors, a` relay bridge in front of said inductive connections, a relay bridge back of said inductive connections, a set of switch springs for each relay bridge, the continuity of each said parallel branch'l being controlled by re'- lay springs of both bridges.

'20. A telephone connect'or provided with a release circuit having normally open parallel branches, a pair of relays, another pair of relays, a setof switch springsl for each pair of relays, the continuity of each said parallel branch being controlled by springs of both pairs of relays.

21. A telephone exchange `'connector provided with a release circuit having normally open parallel branches, a-talking circuit, a relay bridge across said circuit, another relay bridge across' said circuit, a set of switch springs for each bridge, circuit connections -vby which one of said parallel branches is closed by the energizing of one relay bridge when the otherl bridge is denergized, and

. suitable circuit connections by whichv the other parallel branch is closed by the denergizing of the one relay bridge when the other bridge is energized.

22. An automatic telephone exchange connector provided with -a release. circuit havin?l normally open parallel branches, one pair of relays, another pair of relays, a normally 'open and a normally closed switch point inl each said parallel branch, the one pair of "clays controlling the normally open switch pointcin one bridge, the other pair of relays controlling the normally open switch point inthe other bridge, one relay of'the one pair controlling the normally closed switch pointin the parallel branch having. its normally open switch point controlled by the other pair of relays, and a relay of said other pair controlling the normally4 closed switch point in the parallel branch having its normally open switch point controlled by the one pair.

23. An automatic telephone exchange 24. An automatic telephone connectorv provided with a release circuit having two parallel and normally-open branches, parallel voice-current conductors, inductive connections in said voice-current conductors, a relay bridge-in front of said inductive connections, a relay bridge back of said inductivev connections, a set of switch springs for each relay bridge, the continuity of each said 'parallel branch being controlled by relay springs of both bridges,

and means for furnishing talking current through the relay windings.

25. A telephone connector provided with a release circuit havingnormally open parallel branches, a pair of relays, another pair of relays, a set of switch springsy for each pair of relays, thecontinuity of each said parallel branch being controlled by springs of'both pairs of relays, and means for furnishing talking current through the relay windings. i

Q6. A telephone exchange connector provided with a release circuit having normally open parallel branches, a talking circuit, a relay bridge across said circuit, another re.- lay bridge across said circuit, a set of switch springs for each bridge, circuit connections by which one of said parallel branches is closed by the energizing of one relay bridge 4 when theother bridge is denergized, suitable eircuit connections by which the other parallel branch is closed by the denergizing of the one relay bridge when the other bridge is energized, and means `for furnishi-ng talking current through the relay windings.

27. An automatic 'telephone exchange connector provided with a release circuit having normally open parallel branches, 'one pair of relays. another pair of relays, a normallyopen and a normally closed switch point in each said parallel branch, the one pair of relays controlling the' normally open switch point in one bridge, the other pair of relays controlling the normally open switch point in the other bridge, one relay of the one pair controlling the normally closed switch point in the parallel branch having its normally open switch point c ntrolled by the other pair of relays, a re ay of said other pair controlling thenormally closed switch )oint in the parallel branch having its normally open witch point controlled by the one ypair. and means for furnishing talking current through the relay windings.

. spring of each set being grounded. each said parallel branch having a normally closed switch point controlledr by,the springs in one set, a normally open switch point controlled'by the springslin the other set, and means for furnishing talkingvv current l thru h the relay windings.

v29. `n a telephone exchange system, the

ycombination ofa selector provided with a back-release relay,- a connector provided with a rlnger relay, a trunk l1ne iavlng a third conductor, and an energizing circuit y for 4said ringer relay, said circuit including the third trunk line conductor and awinding of the back-release relay.

30. In a telephone exchange system. the combination of aselector provided with a back-release relay, a connector provided with a ringer relay, a trunk line, and an energizing circuit for said ringer relay, said cir cuit including a trunk line conductor and a windin of said lback-release relay.

31. combination of a selector provided with a back-release relay, a connector provided with a ringer relay, and an energizing circuit including the windings of the two relays in series.

32. In a telephone exchange system, the

` combination of a connector provided with a ringer relay, a trunk line leading to said connector, and an energizing circuit for said ringer relay, said circuit including a conductor of said trunk line. v

33. In a telephone exchange system, the combination of a connector provided with a ringer relay, a trunk line leading to said connector, and an energizing circuit for said ringer relay, said circuit including the third conductor of said trunk line.

34. In a. telephone exchange system, the combination of a talking circuit, inductive connections in said circuit, a front relay bridge, a back relay bridge, and a hlgh resistance bridged across the circuit to maintain a slight How of current through the back-bridge relays, for the purpose set forth.

35. In a telephone exchange system, the combination of 'a talking circuit, a step-byn a telephone exchange system, thestep switching mechanism, releasey mechanism. a release circuit, a front relay bridge .provided with springs controlling the said switching mechanism and release circuit, a sid/e switch operated by a private magnet, a. back relay bridge provided with springs tontrollingthe release circuit. a common battery, connections by which the battery is switched into the front-bridge by the energizing of one of the relays of the back-bridge, connec tions by which the lbattery is switched into the back'bridge by the operation of said side switch, said private magnet having an energizing circuit controlled' by springs of said relay bridges. i

36. In a telephone. exchange system, ,the combination of a talking circuit, step-by-step switchingl mechanism. release mechanism. a release circuit, a front relay bridge provided with springs controllingthe said switching mechanism and release circuit, a side switch operated by a private magnet, a back relay bridge vprovided with springs control ling the release circuit, a common battery, co'nnections by which the battery is switched into the front-bridge by the energizing of one of the relays of the back-bridge. vconnections by which the battery switched into the back-bridge by the operation of said side switch, said private magnet havingv an energizing circuit controlled by springs of said relay bridges, and a ringer relay provided with a circuit controlled by the springs of the back relay bridge.

37'. In a telephone exchange system. the 100 combination of a talking circuit, inductive connections in said circuit, a front relay bridge. a back relay bridge. a s'et of` switch springs for each bridge, a private magnet, a sidev switch operated b v the private mag- 105 net, an energizing circuit for said private magnet controlled by springs of both bridges, and means for short-circuiting the winding of said private magnet during conversation.

38. In a telephone exchange system, the combination of a talking circuit, an automatic switch having two pairs of relays maintaining communication between two subscribers. A

40. In a telephone exchange system, an automatic Switching machme provided with 1% step-by-step switching mechanism, a 'private magnet havingsuitable control of said switching mechanism, and means for telnporarily short-circaitingthe winding of said private .magnet (hiring use ofthe switching machine for maintaining communication between subscribers.

4i. In a telephone exchange system. an automatic connector provided with a private magnet. a side switch operated bv the private magnet. and means tor teinporarilv short-circniting the winding ot' said private magnet when 'the side switch has passed to third position. l

2. In al telephone exchange s vstem. an automatic connector provided with a private magnet, a side switch operated by the private ,magnen and' means tor temporarily short-circniting the winding of said private magnet when theside switch has passed ont of normal position.

43'. In atelephone exchange s vstem. the combination ot' an automatic connector provided with a private magnet. a side switch operated bv the private magnet. a called telephone line. and means Yfor ten-iporarilv short-circuiting said private magnet after connection established with the called telephone line.

44. In a telephone vexchange system. the combination of an automatic switching ma'- chine provided with step-b v-step switching mechanism. a private magnet snitabl)v controlling switch switching mechanism. a called telephone line. means for temporarily shortvcircniting the winding ot' said private inagnet while connection is established with the caio .i o -aphone line, and suitaoie means foresta blishing the connection with the telephone line.

l5. In a telephoiie exchange system.A the combination ofy a calling subscribers line, a called subscribers line. automatic switch mechanism for connecting the two lines to-` gether. release niechanisnna release circuit, means for closing the release circuit, a een tralized source of talking current` means consisting of a single pair oiA relay-coils tot' feeding talking current to the calling su'oscribers linefmeans consisting of a single pair of relay-coils for feeding talking current to the called subscribers line.' and means for preventing a closing of the release circuit by the opening of the called subscribers line. A

lo. A telephone connector switch provided with voice current conductors. a condenser in each conductor. a front bridge provided with an electromagnetic device. a back bridge provided with a second electromagneticI device. a batter)v included in both of said bridges. steiib'v-step mechanism controlled b v one ot' said electromagnetic devices. and release mechanism controlled by or of said electroniagnetic devices, said electromagnetic devices constituting the sole or onl;v artificial resistance between the batterv and said talking coiidnctors.

Signed bv'me at Chicago. Cook county, Illinois. this 21st dav of September. 1906.

EDIVRD D. FALS. 'itnesses A. B. Sesam'. Hwmmc'rr M. Minimaal. 

